Heat source unit

Abstract

Provided is a split-type air conditioning device that reduces the risk of a change in the composition ratio of a non-azeotropic refrigerant mixture at the time of installation. In an air conditioning device (1), an outdoor unit (20) and an indoor unit (30) are connected via a liquid refrigerant pipe (5) and a gas refrigerant pipe (6) so as to form a refrigerant circuit (10) at an installation site. A refrigerant with which the refrigerant circuit (10) is filled is a non-azeotropic refrigerant mixture that has a temperature glide of 1°C or more during evaporation and condensation. The length of the liquid refrigerant pipe (5) and the gas refrigerant pipe (6) is determined according to the installation positions of the outdoor unit (20) and the indoor unit (30). A first length (L1), which makes it unnecessary to add a refrigerant to the refrigerant circuit (10), is set in advance as a length of the liquid refrigerant pipe (5) and the gas refrigerant pipe (6). The outdoor unit (20) is filled in advance with an amount of a refrigerant in accordance with a necessary refrigerant amount for the refrigerant circuit (10) when the liquid refrigerant pipe (5) and the gas refrigerant pipe (6) have the first length (L1).

Description

Heat source unit

[0001] The present disclosure relates to a heat source unit of an air conditioner that uses a non-azeotropic refrigerant mixture.

[0002] In a heat pump device using a non-azeotropic refrigerant mixture, there is a risk that the composition ratio may change when the refrigerant is filled on-site. To reduce such a risk, for example, in a heat pump water heater disclosed in Patent Document 1 (International Publication WO 2013 / 111180), a refrigerant is filled for a specific refrigeration cycle (second refrigeration cycle) before shipping from the factory.

[0003] However, the above-mentioned refrigeration cycle is capable of filling with refrigerant before shipping from the factory because a closed refrigerant circuit is already formed at the factory, and it cannot be applied to split-type air conditioners in which the refrigerant circuit is formed by connecting the utilization unit and the heat source unit with piping at the installation site.

[0004] Therefore, there is an issue to be addressed in providing a split-type air conditioner that reduces the risk of the composition ratio of the non-azeotropic refrigerant mixture changing during installation.

[0005] A heat source unit according to a first aspect is a heat source unit configured to be connected to a utilization unit via piping at an installation location to form a refrigerant circuit. The refrigerant filled into the heat source unit is a non-azeotropic refrigerant mixture having a temperature glide of 1°C or more during evaporation and condensation. The heat source unit is pre-filled with an amount of refrigerant required for the refrigerant circuit when the length of the piping is a first length that makes it unnecessary to add refrigerant to the refrigerant circuit.

[0006] It is not easy to charge a non-azeotropic refrigerant mixture on-site while maintaining its composition ratio. Therefore, by charging the refrigerant into the heat source unit in advance, the composition ratio of the non-azeotropic refrigerant mixture can be maintained, eliminating the need for on-site charging.

[0007] A heat source unit according to a second aspect is the heat source unit according to the first aspect, and is configured so that a refrigerant circuit is formed by connecting one utilization unit.

[0008] A heat source unit according to a third aspect is the heat source unit according to the first aspect, configured so that a refrigerant circuit is formed by connecting a plurality of utilization units in parallel.

[0009] A heat source unit according to a fourth aspect is the heat source unit according to any one of the first aspect to the third aspect, in which the temperature glide during evaporation and condensation of the refrigerant is 5° C. or more.

[0010] Among non-azeotropic refrigerants, in the case of a non-azeotropic refrigerant with a temperature glide of 5° C. or more, it is difficult to charge the refrigerant on-site while maintaining the composition ratio. Therefore, in this heat source unit, there is a great advantage in that the composition ratio of the non-azeotropic refrigerant is maintained by charging the refrigerant into the heat source unit in advance.

[0011] The heat source unit of the fifth aspect is a heat source unit of any one of the first aspect to the fourth aspect, and is configured to be connected to a piping of 2.5 minutes or more (outer diameter 7.93 mm) through which a liquid refrigerant or a gas-liquid mixed refrigerant flows.

[0012] When using a non-azeotropic refrigerant mixture with a large pressure drop, the diameter of the pipe through which the liquid refrigerant or gas-liquid mixture refrigerant flows must be increased, which increases the amount of refrigerant to be charged. The greater the amount of refrigerant to be charged, the greater the risk that the refrigerant composition will change during on-site charging. Therefore, in this heat source unit, there is a significant advantage in pre-charging the heat source unit with the refrigerant, as it maintains the composition of the non-azeotropic refrigerant mixture.

[0013] A heat source unit according to a sixth aspect is the heat source unit according to the fifth aspect, wherein the pipe through which the liquid refrigerant or the gas-liquid mixed refrigerant flows is a 2.5-section pipe (outer diameter 7.93 mm).

[0014] If the actual pipe length exceeds the first length, additional refrigerant needs to be charged, increasing the risk of a change in the refrigerant composition ratio. In order to reduce the risk of a change in the composition ratio in such a situation, a 2.5-minute pipe is suitable for the pipe through which the liquid refrigerant or the gas-liquid mixed refrigerant flows, from the viewpoints of both "reducing pressure loss" and "reducing the amount of additional refrigerant charged."

[0015] A heat source unit of a seventh aspect is a heat source unit of any one of the first aspect to the sixth aspect, wherein the amount of refrigerant pre-filled in the heat source unit is two to three times the amount of R32 refrigerant required for the entire refrigerant circuit when R32 refrigerant is filled into a refrigerant circuit whose piping is set to a first length.

[0016] Some non-azeotropic refrigerants require two to three times the amount of R32 refrigerant, which has zero temperature glide, and there is a high risk that the composition ratio of such refrigerants will change when they are filled on-site. Therefore, in this heat source unit, there is a great advantage in that the composition ratio of the non-azeotropic refrigerant mixture is maintained by filling the heat source unit in advance.

[0017] A heat source unit according to an eighth aspect is the heat source unit according to any one of the first aspect to the seventh aspect, wherein the first length is 30 m.

[0018] A heat source unit according to a ninth aspect is the heat source unit according to any one of the first to eighth aspects, further comprising a first shut-off valve, a second shut-off valve, and a heat source circuit. The heat source circuit is a refrigerant flow path from the first shut-off valve to the second shut-off valve and is configured to form part of the refrigerant circuit. The heat source circuit includes a compressor, a heat exchanger, and a pressure reducer. The compressor, heat exchanger, and pressure reducer are connected in sequence. The heat source circuit further includes a high-pressure receiver connected between the heat exchanger and the pressure reducer.

[0019] In this heat source unit, the amount of refrigerant that can be pre-charged can include an amount of refrigerant equivalent to the internal volume of the high-pressure receiver.

[0020] A heat source unit according to a tenth aspect is the heat source unit according to the ninth aspect, wherein the volume ratio of the high-pressure receiver to the heat exchanger is within the range of 0.04 to 0.6.

[0021] The present invention relates to a refrigerant circuit for an air conditioner, and a method for manufacturing the same, comprising: providing a refrigerant circuit for an air conditioner according to a first embodiment of the present disclosure; providing a table showing the composition ratio and temperature glide of a non-azeotropic refrigerant mixture used in the present embodiment; and providing a circuit diagram of a refrigerant circuit for an air conditioner according to a second embodiment of the present disclosure.

[0022] <First embodiment> (1) Configuration of air conditioner 1 Fig. 1 is a circuit diagram of a refrigerant circuit 10 of an air conditioner 1 according to a first embodiment of the present disclosure. In the air conditioner 1, an indoor unit 30, which is one utilization unit, is connected to an outdoor unit 20, which is a heat source unit, via a liquid refrigerant pipe 5 and a gas refrigerant pipe 6.

[0023] The refrigerant filled into the refrigerant circuit 10 is a non-azeotropic refrigerant mixture that has a temperature glide of 1° C. or more during evaporation and condensation. Typically, the refrigerant is filled after the outdoor unit 20 and the indoor unit 30 are connected via the liquid refrigerant piping 5 and the gas refrigerant piping 6 at the installation location of the air conditioning apparatus 1.

[0024] However, in the present embodiment, before the liquid refrigerant pipe 5 and the gas refrigerant pipe 6 are connected, the outdoor unit 20 is pre-filled with the amount of refrigerant required for the entire refrigerant circuit 10 when the liquid refrigerant pipe 5 and the gas refrigerant pipe 6 are set to the predetermined first length L1, regardless of the actual lengths of the liquid refrigerant pipe 5 and the gas refrigerant pipe 6.

[0025] (1-1) Outdoor Unit 20 The outdoor unit 20 includes a compressor 11, a four-way switching valve 13, an outdoor heat exchanger 15, a bridge circuit unit 17, a liquid-gas heat exchanger 19, a high-pressure receiver 21, an expansion valve 23, a liquid-side shut-off valve 25, a gas-side shut-off valve 26, and an accumulator 27.

[0026] The compressor 11, four-way switching valve 13, outdoor heat exchanger 15, bridge circuit section 17, liquid-gas heat exchanger 19, high-pressure receiver 21, expansion valve 23, and accumulator 27 are arranged in the refrigerant flow path from the liquid-side shut-off valve 25 to the gas-side shut-off valve 26, and constitute a heat source circuit 20a, which is part of the refrigerant circuit 10.

[0027] The outdoor unit 20 is also provided with an outdoor fan 29 that generates an airflow to promote heat exchange between the air and the outdoor heat exchanger 15 .

[0028] (1-1-1) Compressor 11 The compressor 11 has a suction port 11a and a discharge port 11b. The refrigerant flows into the compressor 11 through the suction port 11a, is compressed to a high temperature and high pressure, and flows out from the discharge port 11b.

[0029] (1-1-2) Four-way switching valve 13 The four-way switching valve 13 has a first port P1, a second port P2, a third port P3, and a fourth port P4. The first port P1 is connected to the discharge port 11b of the compressor 11. The second port P2 is connected to the outdoor heat exchanger 15. The third port P3 is connected to the suction port 11a of the compressor 11 via the liquid-gas heat exchanger 19 and the accumulator 27. The fourth port P4 is connected to the gas-side shut-off valve 26.

[0030] (1-1-3) Outdoor Heat Exchanger 15 The outdoor heat exchanger 15 is an air heat exchanger. The outdoor heat exchanger 15 exchanges heat between the refrigerant flowing inside and the outside air sent from the outdoor fan 29. In this embodiment, a fin-and-tube heat exchanger is used as the outdoor heat exchanger 15.

[0031] (1-1-4) Bridge Circuit Unit 17 The bridge circuit unit 17 has four check valves 17a, 17b, 17c, and 17d connected in a bridge configuration. A first connection point S1 between the check valves 17a and 17b is connected to the outdoor heat exchanger 15. A second connection point S2 between the check valves 17a and 17c is connected to the expansion valve 23. A third connection point S3 between the check valves 17c and 17d is connected to the liquid-side shutoff valve 25. A fourth connection point S4 between the check valves 17b and 17d is connected to the liquid pipe 19a of the liquid-gas heat exchanger 19.

[0032] (1-1-5) Liquid-Gas Heat Exchanger 19 The liquid-gas heat exchanger 19 exchanges heat between a high-pressure refrigerant flowing through a liquid pipe 19a and a low-pressure refrigerant flowing through a gas pipe 19b. The liquid-gas heat exchanger 19 is a double-pipe heat exchanger.

[0033] (1-1-6) High-Pressure Receiver 21 The high-pressure receiver 21 temporarily stores the refrigerant supercooled by the liquid-gas heat exchanger 19 .

[0034] (1-1-7) Expansion Valve 23 The expansion valve 23 is disposed between the outlet of the high-pressure receiver 21 and the second connection point S2 of the bridge circuit unit 17. The expansion valve 23 reduces the pressure of the refrigerant flowing from the high-pressure receiver 21 to the second connection point S2 of the bridge circuit unit 17 to a predetermined low pressure.

[0035] (1-1-8) Liquid-Side Shut-Off Valve 25 The liquid-side shut-off valve 25 is connected between the third connection point S3 of the bridge circuit unit 17 and the indoor heat exchanger 35. The liquid-side shut-off valve 25 and the indoor heat exchanger 35 are connected by the liquid refrigerant piping 5.

[0036] (1-1-9) Gas-side shut-off valve 26 The gas-side shut-off valve 26 is connected in series with the four-way switching valve 13 between the four-way switching valve 13 and the indoor heat exchanger 35. The gas-side shut-off valve 26 and the indoor heat exchanger 35 are connected by the gas refrigerant piping 6.

[0037] (1-1-10) Accumulator 27 The accumulator 27 is connected between the four-way switching valve 13 and the suction port 11a of the compressor 11. The accumulator 24 recovers the liquid refrigerant that was not gasified in the evaporator, and prevents the liquid refrigerant from flowing into the suction port 11a of the compressor 11.

[0038] (1-1-11) Outdoor Fan 29 The outdoor fan 29 generates an air flow to promote heat exchange between the air and the refrigerant flowing inside the outdoor heat exchanger 15. The outdoor fan 29 is a propeller fan.

[0039] (1-2) Indoor Unit 30 The indoor unit 30 is provided with an indoor heat exchanger 35. The indoor unit 30 also has an indoor fan 37 that generates airflow to promote heat exchange between the air and the indoor heat exchanger 35.

[0040] (1-2-1) Indoor Heat Exchanger 35 The indoor heat exchanger 35 is an air heat exchanger. The indoor heat exchanger 35 exchanges heat between the refrigerant flowing inside and the indoor air sent from the indoor fan 37. In this embodiment, a fin-and-tube heat exchanger is used as the indoor heat exchanger 35.

[0041] One end of the indoor heat exchanger 35 is connected to the liquid-side shutoff valve 25 via a liquid refrigerant pipe 5 , and the other end is connected to the gas-side shutoff valve 26 via a gas refrigerant pipe 6 .

[0042] (1-2-2) Indoor Fan 37 The indoor fan 37 generates an airflow to promote heat exchange between the indoor air and the refrigerant flowing inside the indoor heat exchanger 35. The indoor fan 37 is a sirocco fan.

[0043] (1-3) Liquid refrigerant piping 5 and gas refrigerant piping 6 The liquid refrigerant piping 5 and gas refrigerant piping 6 connect the outdoor unit 20 and the indoor unit 30 to form the refrigerant circuit 10. The lengths of the liquid refrigerant piping 5 and the gas refrigerant piping 6 are determined depending on the installation positions of the outdoor unit 20 and the indoor unit 30.

[0044] The liquid refrigerant pipe 5 connects the liquid-side shutoff valve 25 of the outdoor unit 20 to a refrigerant inlet of the indoor heat exchanger 35 of the indoor unit 30 during cooling operation (a refrigerant outlet during heating operation).

[0045] The gas refrigerant pipe 6 connects the gas side shutoff valve 26 of the outdoor unit 20 to a refrigerant outlet of the indoor heat exchanger 35 of the indoor unit 30 during cooling operation (a refrigerant inlet during heating operation).

[0046] When using a non-azeotropic refrigerant mixture with a large pressure loss, the diameter of the liquid refrigerant pipe 5 must be increased, preferably a 2.5-minute pipe (outer diameter 7.93 mm) or larger. However, the larger the refrigerant filling amount, the greater the risk that the refrigerant composition ratio will change during on-site filling. Therefore, in this air conditioning system 1, there is a significant advantage in pre-filling the outdoor unit 20 with the refrigerant mixture, in that the composition ratio of the non-azeotropic refrigerant mixture can be maintained.

[0047] However, if the actual piping lengths of the liquid refrigerant pipe 5 and the gas refrigerant pipe 6 exceed the first length L1, additional refrigerant charging will be required, increasing the risk of a change in the refrigerant composition ratio. In order to reduce the risk of a change in the composition ratio in such a situation, a 2.5-section pipe is suitable for the liquid refrigerant pipe 5 in this air conditioning device 1 from the standpoints of both "reducing pressure loss" and "reducing the amount of additional refrigerant charged."

[0048] (1-4) Control Unit 40 The control unit 40 controls the operating frequency of the compressor 11, controls the switching of the four-way switching valve 13, and controls the opening of the expansion valve 23. The control unit 40 is configured with a microprocessor and a printed circuit board equipped with a memory.

[0049] (1-5) Refrigerant The refrigerant used in this embodiment is a non-azeotropic refrigerant mixture. A non-azeotropic refrigerant mixture is a mixture of two or more refrigerants with different boiling points. Because a refrigerant with a higher boiling point condenses before a refrigerant with a lower boiling point, the isotherm of a non-azeotropic refrigerant mixture slopes downward to the right from the saturated liquid line to the saturated vapor line. Therefore, a temperature glide occurs between the saturated liquid line and the saturated vapor line under the same pressure conditions.

[0050] 2 is a table showing the composition ratios and temperature glides of the non-azeotropic refrigerant mixtures used in this embodiment. The physical properties of R454B, R454C, and R474A are determined based on the composition ratios shown in FIG.

[0051] (2) Operation of the Air Conditioning Apparatus 1 Here, the operation of the air conditioning apparatus 1 will be described using cooling operation and heating operation as examples.

[0052] (2-1) Cooling Operation During cooling operation, the four-way selector valve 13 is maintained in the state shown by the solid line in Fig. 1. The high-temperature, high-pressure gas refrigerant discharged from the compressor 11 flows into the outdoor heat exchanger 15 via the four-way selector valve 13, where it exchanges heat with the outdoor air and condenses.

[0053] The condensed refrigerant passes through the first connection point S1, the check valve 17b, and the fourth connection point S4 of the bridge circuit unit 17 and flows into the liquid pipe 19a of the liquid-gas heat exchanger 19. The refrigerant flowing through the liquid pipe 19a exchanges heat with the refrigerant flowing through the gas pipe 19b and is subcooled.

[0054] The refrigerant that flows through the liquid pipe 19a is temporarily stored in the high-pressure receiver 21. The refrigerant that flows out of the high-pressure receiver 21 is reduced in pressure to a predetermined low level by the expansion valve 23. The refrigerant reduced in pressure by the expansion valve 23 flows into the indoor heat exchanger 35 via the second connection point S2, the check valve 17c, and the third connection point S3 of the bridge circuit unit 17. In the indoor heat exchanger 35, the refrigerant exchanges heat with the indoor air and evaporates. The indoor air cooled by the evaporation of the refrigerant is then blown into the room by the corresponding indoor fan 37, cooling the room.

[0055] The refrigerant evaporated in the indoor heat exchanger 35 flows through the gas refrigerant pipe 6 and the four-way switching valve 13 into the gas pipe 19 b of the liquid-gas heat exchanger 19 .

[0056] The refrigerant flowing through the gas pipe 19b exchanges heat with the refrigerant flowing through the liquid pipe 19a and becomes superheated vapor. The refrigerant flowing through the gas pipe 19b passes through the accumulator 27 and is sucked into the compressor 11.

[0057] (2-2) Heating Operation During heating operation, the four-way switching valve 13 is maintained in the state shown by the dashed line in Fig. 1. The high-temperature, high-pressure gas refrigerant discharged from the compressor 11 flows into the indoor heat exchanger 35 via the four-way switching valve 13, where it exchanges heat with the indoor air and condenses.

[0058] The indoor air heated by heat exchange with the refrigerant is blown into the room by the indoor fan 37, heating the room.

[0059] The refrigerant condensed in the indoor heat exchanger 35 flows through the liquid refrigerant pipe 5 and reaches the bridge circuit unit 17. The refrigerant passes through the third connection point S3, check valve 17d, and fourth connection point S4 of the bridge circuit unit 17 and flows into the liquid pipe 19a of the liquid-gas heat exchanger 19. The refrigerant flowing through the liquid pipe 19a exchanges heat with the refrigerant flowing through the gas pipe 19b and is subcooled.

[0060] The refrigerant that flows through the liquid pipe 19a is temporarily stored in the high-pressure receiver 21. The refrigerant that flows out of the high-pressure receiver 21 is reduced in pressure to a predetermined low level by the expansion valve 23. The reduced-pressure refrigerant passes through the second connection point S2 of the bridge circuit unit 17, the check valve 17a, and the first connection point S1 and flows into the outdoor heat exchanger 15. In the outdoor heat exchanger 15, the refrigerant exchanges heat with the outdoor air and evaporates.

[0061] The refrigerant evaporated in the outdoor heat exchanger 15 flows through the four-way selector valve 13 into the gas pipe 19b of the liquid-gas heat exchanger 19. The refrigerant flowing through the gas pipe 19b exchanges heat with the refrigerant flowing through the liquid pipe 19a and becomes superheated vapor. The refrigerant flowing through the gas pipe 19b passes through the accumulator 27 and is sucked into the compressor 11.

[0062] (3) Refrigerant Charging into the Outdoor Unit 20 Normally, the refrigerant is charged at the installation location of the air conditioning apparatus 1 after the outdoor unit 20 and the indoor unit 30 are connected via the liquid refrigerant piping 5 and the gas refrigerant piping 6. The lengths of the liquid refrigerant piping 5 and the gas refrigerant piping 6 are determined depending on the installation positions of the outdoor unit 20 and the indoor unit 30.

[0063] However, the air conditioning apparatus 1 of this embodiment uses a non-azeotropic refrigerant mixture, and there is a high risk that the composition ratio will change when the refrigerant is charged after installation, so it is necessary to reduce this risk.

[0064] Therefore, the heat source circuit 20a of the outdoor unit 20 is pre-filled with an amount of refrigerant corresponding to the amount of refrigerant required in the refrigerant circuit 10 when the liquid refrigerant piping 5 and the gas refrigerant piping 6 have a predetermined first length L1. The first length L1 is a length that makes it unnecessary to additionally charge refrigerant into the refrigerant circuit 10 formed by connecting the outdoor unit 20 and the indoor unit 30 via the liquid refrigerant piping 5 and the gas refrigerant piping 6. In this embodiment, the first length L1 is set to 30 m.

[0065] The refrigerant is filled into the outdoor heat exchanger 15, the liquid-gas heat exchanger 19, the high-pressure receiver 21, the accumulator 27, and the pipes connecting these, which are included in the heat source circuit 20a of the outdoor unit 20.

[0066] The amount of non-azeotropic refrigerant mixture pre-filled in the outdoor unit 20 is, for example, two to three times the amount of R32 refrigerant required for the entire refrigerant circuit 10 when R32 refrigerant is filled into the refrigerant circuit 10 in which the liquid refrigerant piping 5 and the gas refrigerant piping 6 are set to the first length.

[0067] In this embodiment, in order to increase the amount of refrigerant that can be pre-filled into the outdoor unit 20, the diameter of the pipes in the outdoor unit 20 is made larger than the diameter of the pipes in the indoor unit 30.

[0068] In addition, in order to ensure that the amount of refrigerant pre-filled in the outdoor unit 20 is sufficient for the amount of refrigerant required for the entire refrigerant circuit 10, the volume ratio of the outdoor heat exchanger 15 to the indoor heat exchanger 35 is set to 3 or more.

[0069] Furthermore, by setting the volume ratio of the high-pressure receiver 21 to the outdoor heat exchanger 15 within the range of 0.04 to 0.6, the amount of refrigerant pre-filled in the outdoor unit 20 can easily satisfy the amount of refrigerant required for the entire refrigerant circuit 10.

[0070] The installation work of the air conditioning device 1 comprises the steps of installing the outdoor unit 20 and the indoor unit 30 at the installation location, connecting the outdoor unit 20 and the indoor unit 30 via the liquid refrigerant piping 5 and the gas refrigerant piping 6, and sending the refrigerant filled in the outdoor unit 20 to the refrigerant circuit 10.

[0071] In the process in which the refrigerant filled in the outdoor unit 20 is sent to the refrigerant circuit 10, the liquid-side shut-off valve 25 and the gas-side shut-off valve 26 are opened, thereby filling the refrigerant circuit 10.

[0072] (4) Features (4-1) In the air conditioning apparatus 1, the outdoor unit 20 and the indoor unit 30 are connected via a liquid refrigerant pipe 5 and a gas refrigerant pipe 6 at the installation location to form a refrigerant circuit 10. The refrigerant filled into the refrigerant circuit 10 is a non-azeotropic refrigerant mixture having a temperature glide of 1°C or more during evaporation and condensation. The lengths of the liquid refrigerant pipe 5 and the gas refrigerant pipe 6 are determined according to the installation positions of the outdoor unit 20 and the indoor unit 30. The lengths of the liquid refrigerant pipe 5 and the gas refrigerant pipe 6 are set in advance to a first length L1 (for example, L1 = 30 m) at which additional refrigerant does not need to be charged into the refrigerant circuit 10. The outdoor unit 20 is pre-filled with an amount of refrigerant corresponding to the amount of refrigerant required in the refrigerant circuit 10 when the liquid refrigerant pipe 5 and the gas refrigerant pipe 6 have the first length L1.

[0073] It is not easy to charge a non-azeotropic refrigerant mixture on-site while maintaining its composition ratio. Therefore, in this air conditioning system 1, the outdoor unit 20 is pre-charged with the refrigerant, eliminating the need for on-site charging, thereby maintaining the composition ratio of the non-azeotropic refrigerant mixture.

[0074] (4-2) In particular, when using R454C, which has a temperature glide of 5° C. or more during evaporation and condensation, it is difficult to charge the refrigerant on-site while maintaining the composition ratio. Therefore, in this air conditioning system 1, there is a significant advantage in that the composition ratio of the non-azeotropic refrigerant mixture is maintained by pre-filling the outdoor unit 20 with the refrigerant.

[0075] (4-3) The liquid refrigerant pipe 5 is preferably a 2.5-minute pipe (outer diameter 7.93 mm) or longer. When using a non-azeotropic refrigerant mixture with a large pressure loss, the diameter of the liquid refrigerant pipe 5 must be increased, which increases the amount of refrigerant to be charged. The greater the amount of refrigerant to be charged, the greater the risk that the refrigerant composition will change during on-site charging. Therefore, with this air conditioning device 1, there is a significant advantage in pre-charging the outdoor unit 20 with the refrigerant, in that the composition of the non-azeotropic refrigerant mixture can be maintained.

[0076] However, if the actual piping lengths of the liquid refrigerant pipe 5 and the gas refrigerant pipe 6 exceed the first length L1, additional refrigerant charging will be required, further increasing the risk of a change in the refrigerant composition ratio. In order to reduce the risk of a change in the composition ratio in such a situation, a 2.5-section pipe is appropriate for the liquid refrigerant pipe 5 from the standpoints of both "reducing pressure loss" and "reducing the amount of additional refrigerant charged."

[0077] (4-4) The amount of the non-azeotropic refrigerant mixture pre-filled in the outdoor unit 20 is two to three times the amount of R32 refrigerant that would be required for the entire refrigerant circuit 10 if a single R32 refrigerant were to be filled into the refrigerant circuit 10 in which the liquid refrigerant pipe 5 and the gas refrigerant pipe 6 are set to the first length L1.

[0078] Some non-azeotropic refrigerants require two to three times the amount of R32 refrigerant, which has zero temperature glide, and there is a high risk that the composition ratio of such refrigerants will change when they are filled on-site. Therefore, in this air conditioning system 1, there is a great advantage in that the composition ratio of the non-azeotropic refrigerant is maintained by filling the outdoor unit 20 with the refrigerant in advance.

[0079] (4-5) Since the diameter of the pipes in the outdoor unit 20 is larger than the diameter of the pipes in the indoor unit 30, the amount of refrigerant that can be pre-filled into the outdoor unit 20 can be increased.

[0080] (4-6) The volume ratio of the outdoor heat exchanger 15 to the indoor heat exchanger 35 is equal to or greater than 3. This allows the amount of refrigerant pre-filled in the outdoor unit 20 to satisfy the amount of refrigerant required for the entire refrigerant circuit 10.

[0081] (4-7) The high-pressure receiver 21 is connected between the outdoor heat exchanger 15 and the expansion valve 23. The volume ratio of the high-pressure receiver 21 to the outdoor heat exchanger 15 is within a range of 0.04 to 0.6. The amount of refrigerant that can be pre-charged into the outdoor unit 20 can include an amount of refrigerant equivalent to the internal volume of the high-pressure receiver 21.

[0082] (4-8) The refrigerant circuit 10 is provided with a liquid-gas heat exchanger 19 that exchanges heat between a high-pressure liquid refrigerant and a low-pressure gas refrigerant. The liquid-gas heat exchanger 19 is a double-pipe heat exchanger. The amount of refrigerant that can be pre-filled into the outdoor unit 20 can include an amount of refrigerant equivalent to the internal volume of the liquid-gas heat exchanger 19.

[0083] (5) Others The worker installing the air conditioning device 1 determines whether the lengths of the liquid refrigerant piping 5 and the gas refrigerant piping 6 required for the installation of the air conditioning device 1 are equal to or shorter than the first length L1.

[0084] If the lengths of the liquid refrigerant piping 5 and the gas refrigerant piping 6 are equal to or less than the first length L1, the refrigerant amount filled in the outdoor unit 20 is equal to or greater than the required refrigerant amount, and therefore the additional refrigerant filling step is not necessary. Therefore, the additional refrigerant filling step is not performed, and the outdoor unit 20 and the indoor unit 30 are connected via the liquid refrigerant piping 5 and the gas refrigerant piping 6, and then the installation work is completed.

[0085] In other words, the amount of refrigerant filled in the outdoor unit 20 is equal to or greater than the amount of refrigerant required in the refrigerant circuit 10 when the liquid refrigerant pipe 5 and the gas refrigerant pipe 6 are equal to or shorter than the first length L1.

[0086] On the other hand, if the lengths of the liquid refrigerant pipe 5 and the gas refrigerant pipe 6 exceed the first length L1, the refrigerant pre-filled in the outdoor unit 20 is insufficient to meet the required amount of refrigerant, and therefore a process of additionally filling the refrigerant is required.

[0087] Therefore, a refrigerant additional charging step is performed, and an amount of refrigerant corresponding to the lengths of the liquid refrigerant pipe 5 and the gas refrigerant pipe 6 is additionally charged into the refrigerant circuit 10. The refrigerant is additionally charged through the service port of the liquid side shut-off valve 25 or the gas side shut-off valve 26, for example.

[0088] <Second embodiment> (1) Configuration of air conditioning apparatus 100 Fig. 3 is a circuit diagram of a refrigerant circuit 110 of an air conditioning apparatus 100 according to a second embodiment of the present disclosure. The air conditioning apparatus 100 is a multi-room air conditioning apparatus in which a plurality of indoor units 30a, 30b, 30c, and 30d, which are utilization units, are connected in parallel to one outdoor unit 120, which is a heat source unit.

[0089] Here, the same names and symbols are given to the components common to the first embodiment, and the description thereof will be omitted, and only the parts different from the first embodiment will be described.

[0090] (1-1) Outdoor Unit 120 In the outdoor unit 120, the compressor 11, four-way switching valve 13, outdoor heat exchanger 15, bridge circuit section 17, liquid-gas heat exchanger 19, high-pressure receiver 21, expansion valve 23, and accumulator 27 are provided in the refrigerant flow path from liquid-side shut-off valves 25a, 25b, 25c, and 25d to the gas-side shut-off valve 26, and form a heat source circuit 120a, which is part of the refrigerant circuit 10.

[0091] The compressor 11, four-way switching valve 13, outdoor heat exchanger 15, bridge circuit unit 17, liquid-gas heat exchanger 19, high-pressure receiver 21, expansion valve 23, and filling refrigerant are the same as those in the first embodiment, so description thereof will be omitted.

[0092] (1-1-1) Second Expansion Valves 24a, 24b, 24c, 24d The four second expansion valves 24a, 24b, 24c, 24d are connected in parallel. Each second expansion valve 24a, 24b, 24c, 24d is connected in series to a corresponding liquid-side shut-off valve 25a, 25b, 25c, 25d.

[0093] (1-1-2) Liquid-side shut-off valves 25a, 25b, 25c, 25d Each of the liquid-side shut-off valves 25a, 25b, 25c, 25d is connected in series with the corresponding second expansion valve 24a, 24b, 24c, 24d between the corresponding second expansion valve 24a, 24b, 24c, 24d and the corresponding indoor heat exchanger 35a, 35b, 35c, 35d.

[0094] The liquid-side shutoff valves 25a, 25b, 25c, and 25d are connected to the corresponding indoor heat exchangers 35a, 35b, 35c, and 35d by corresponding liquid refrigerant pipes 5a, 5b, 5c, and 5d, respectively.

[0095] (1-2) Indoor Units 30a, 30b, 30c, and 30d Indoor heat exchangers 35a, 35b, 35c, and 35d are disposed in the indoor units 30a, 30b, 30c, and 30d, respectively.

[0096] In addition, indoor fans 37a, 37b, 37c, 37d that generate airflow are arranged in each indoor unit 30a, 30b, 30c, 30d to promote heat exchange between the air and the indoor heat exchangers 35a, 35b, 35c, 35d.

[0097] (1-2-1) Indoor Heat Exchangers 35a, 35b, 35c, 35d The indoor heat exchangers 35a, 35b, 35c, 35d are air heat exchangers. The indoor heat exchangers 35a, 35b, 35c, 35d exchange heat between the refrigerant flowing therethrough and the indoor air sent from the corresponding indoor fans 37a, 37b, 37c, 37d. In this embodiment, fin-and-tube heat exchangers are used as the indoor heat exchangers 35a, 35b, 35c, 35d.

[0098] One end of the indoor heat exchanger 35a is connected to the liquid side shut-off valve 25a via the liquid refrigerant pipe 5a, and the other end is connected to the gas side shut-off valve 26. Furthermore, one end of the indoor heat exchanger 35b is connected to the liquid side shut-off valve 25b via the liquid refrigerant pipe 5b, and the other end is connected to the gas side shut-off valve 26 via the gas refrigerant pipe 6. Furthermore, one end of the indoor heat exchanger 35c is connected to the liquid side shut-off valve 25c via the liquid refrigerant pipe 5c, and the other end is connected to the gas side shut-off valve 26 via the gas refrigerant pipe 6. Furthermore, one end of the indoor heat exchanger 35d is connected to the liquid side shut-off valve 25d via the liquid refrigerant pipe 5d, and the other end is connected to the gas side shut-off valve 26 via the gas refrigerant pipe 6.

[0099] (1-2-2) Indoor Fans 37a, 37b, 37c, 37d The indoor fans 37a, 37b, 37c, 37d generate airflow to promote heat exchange between the air and the refrigerant flowing inside the corresponding indoor heat exchangers 35a, 35b, 35c, 35d. The indoor fans 37a, 37b, 37c, 37d are sirocco fans.

[0100] (1-3) Liquid refrigerant pipes 5a, 5b, 5c, 5d The liquid refrigerant pipes 5a, 5b, 5c, 5d and the gas refrigerant pipe 6 connect the outdoor unit 120 and the indoor units 30a, 30b, 30c, 30d, and form the refrigerant circuit 110. The lengths of the liquid refrigerant pipes 5a, 5b, 5c, 5d and the gas refrigerant pipe 6 are determined depending on the installation positions of the outdoor unit 120 and the indoor units 30a, 30b, 30c, 30d.

[0101] The liquid refrigerant pipes 5a, 5b, 5c, and 5d connect the corresponding liquid-side shut-off valves 25a, 25b, 25c, and 25d of the outdoor unit 120 to the refrigerant inlets of the corresponding indoor heat exchangers 35a, 35b, 35c, and 35d during cooling operation (refrigerant outlets during heating operation).

[0102] The gas refrigerant pipe 6 connects the gas-side shutoff valve 26 of the outdoor unit 120 to the refrigerant outlets of the indoor heat exchangers 35a, 35b, 35d, and 35c during cooling operation (refrigerant inlets during heating operation).

[0103] When using a non-azeotropic refrigerant mixture with a large pressure loss, the diameter of the liquid refrigerant pipes 5a, 5b, 5c, and 5d must be increased, preferably to 2.5 mm (outer diameter 7.93 mm) or greater. However, the larger the refrigerant filling amount, the greater the risk of the refrigerant composition changing during on-site filling. Therefore, in this air conditioning system 100, there is a significant advantage in pre-filling the outdoor unit 120 with the refrigerant mixture, in that the composition ratio of the non-azeotropic refrigerant mixture can be maintained.

[0104] However, if the actual piping lengths of the liquid refrigerant pipes 5a, 5b, 5c, and 5d and the gas refrigerant pipe 6 exceed the first length L1, additional refrigerant charging will be required, increasing the risk of a change in the refrigerant composition ratio. To reduce the risk of a change in the composition ratio in such a situation, in this air conditioning apparatus 100, from the standpoints of both "reducing pressure loss" and "reducing the amount of refrigerant that needs to be additionally charged," 2.5-section pipes are suitable for the liquid refrigerant pipes 5a, 5b, 5c, and 5d.

[0105] (1-4) Control Unit 40 The control unit 40 controls the operating frequency of the compressor 11, the switching of the four-way switching valve 13, the opening of the expansion valve 23, and the opening of the second expansion valves 24a, 24b, 24c, and 24d. The control unit 40 is configured with a microprocessor and a printed circuit board equipped with a memory.

[0106] (2) Operation of the Air Conditioning Apparatus 100 Here, the operation of the air conditioning apparatus 100 will be described using cooling operation and heating operation as examples.

[0107] (2-1) Cooling Operation During cooling operation, the four-way selector valve 13 is maintained in the state shown by the solid line in Fig. 3. The expansion valve 23 is controlled so that its valve opening is fully open. The high-temperature, high-pressure gas refrigerant discharged from the compressor 11 flows into the outdoor heat exchanger 15 via the four-way selector valve 13, where it exchanges heat with the outdoor air and condenses.

[0108] The condensed refrigerant passes through the first connection point S1, the check valve 17b, and the fourth connection point S4 of the bridge circuit unit 17 and flows into the liquid pipe 19a of the liquid-gas heat exchanger 19. The refrigerant flowing through the liquid pipe 19a exchanges heat with the refrigerant flowing through the gas pipe 19b and is subcooled.

[0109] The refrigerant flowing through the liquid pipe 19a is temporarily stored in the high-pressure receiver 21. The refrigerant flowing out of the high-pressure receiver 21 passes through the fully open expansion valve 23, passes through the second connection point S2, check valve 17c, and third connection point S3 of the bridge circuit unit 17, and is then diverted to each of the second expansion valves 24a, 24b, 24c, and 24d, where it is reduced to a predetermined low pressure. The refrigerant reduced in pressure by each of the second expansion valves 24a, 24b, 24c, and 24d exchanges heat with indoor air in the corresponding indoor heat exchangers 35a, 35b, 35c, and 35d, where it evaporates. The indoor air cooled by the evaporation of the refrigerant is then blown into the room by the corresponding indoor fans 37a, 37b, 37c, and 37d, cooling the room.

[0110] The refrigerants evaporated in the indoor heat exchangers 35 a , 35 b , 35 c , and 35 d join together in the gas refrigerant pipe 6 , pass through the four-way selector valve 13 , and flow into the gas pipe 19 b of the liquid-gas heat exchanger 19 .

[0111] The refrigerant flowing through the gas pipe 19b exchanges heat with the refrigerant flowing through the liquid pipe 19a and becomes superheated vapor. The refrigerant flowing through the gas pipe 19b passes through the accumulator 27 and is sucked into the compressor 11.

[0112] (2-2) Heating Operation During heating operation, the four-way selector valve 13 is maintained in the state shown by the dashed line in Fig. 3. Furthermore, each of the second expansion valves 24a, 24b, 24c, and 24d is controlled so that its valve opening is fully open. The high-temperature, high-pressure gas refrigerant discharged from the compressor 11 flows through the four-way selector valve 13 into each of the indoor heat exchangers 35a, 35b, 35c, and 35d, where it exchanges heat with the indoor air and condenses.

[0113] The indoor air heated by heat exchange with the refrigerant is blown into the room by the corresponding indoor fans 37a, 37b, 37c, and 37d, thereby heating the room.

[0114] The refrigerant condensed in each indoor heat exchanger 35a, 35b, 35c, 35d flows into the corresponding liquid refrigerant pipe 5a, 5b, 5c, 5d and reaches the corresponding second expansion valve 24a, 24b, 24c, 24d. Because each second expansion valve 24a, 24b, 24c, 24d is fully open, the refrigerant passes through each second expansion valve 24a, 24b, 24c, 24d and joins without being reduced in pressure.

[0115] The refrigerant then passes through the third connection point S3, the check valve 17d, and the fourth connection point S4 of the bridge circuit 17 and flows into the liquid pipe 19a of the liquid-gas heat exchanger 19. The refrigerant flowing through the liquid pipe 19a exchanges heat with the refrigerant flowing through the gas pipe 19b and is subcooled.

[0116] The refrigerant that flows through the liquid pipe 19a is temporarily stored in the high-pressure receiver 21. The refrigerant that flows out of the high-pressure receiver 21 is reduced in pressure to a predetermined low level by the expansion valve 23. The reduced-pressure refrigerant passes through the second connection point S2 of the bridge circuit unit 17, the check valve 17a, and the first connection point S1 and flows into the outdoor heat exchanger 15. In the outdoor heat exchanger 15, the refrigerant exchanges heat with the outdoor air and evaporates.

[0117] The refrigerant evaporated in the outdoor heat exchanger 15 flows through the four-way selector valve 13 into the gas pipe 19b of the liquid-gas heat exchanger 19. The refrigerant flowing through the gas pipe 19b exchanges heat with the refrigerant flowing through the liquid pipe 19a and becomes superheated vapor. The refrigerant flowing through the gas pipe 19b passes through the accumulator 27 and is sucked into the compressor 11.

[0118] (3) Refrigerant Charging into the Outdoor Unit 120 Normally, refrigerant is charged at the installation location of the air conditioning apparatus 100 after the outdoor unit 120 and the indoor units 30a, 30b, 30c, 30d are connected via the liquid refrigerant pipes 5a, 5b, 5c, 5d and the gas refrigerant pipe 6. The lengths of the liquid refrigerant pipes 5a, 5b, 5c, 5d and the gas refrigerant pipe 6 are determined depending on the installation locations of the outdoor unit 120 and the indoor units 30a, 30b, 30c, 30d.

[0119] However, the air conditioning apparatus 100 of this embodiment uses a non-azeotropic refrigerant mixture, and there is a high risk that the composition ratio will change when the refrigerant is charged after installation, so it is necessary to reduce this risk.

[0120] Therefore, the heat source circuit 120a of the outdoor unit 120 is pre-filled with an amount of refrigerant corresponding to the amount of refrigerant required in the refrigerant circuit 110 when the liquid refrigerant pipes 5a, 5b, 5c, and 5d and the gas refrigerant pipe 6 have a predetermined first length L1. The first length L1 is a length that eliminates the need to additionally fill the refrigerant into the refrigerant circuit 110 formed by connecting the outdoor unit 120 and the indoor units 30a, 30b, 30c, and 30d via the liquid refrigerant pipes 5a, 5b, 5c, and 5d and the gas refrigerant pipe 6. In this embodiment, the first length L1 is set to 30 m.

[0121] The refrigerant is filled into the outdoor heat exchanger 15, the liquid-gas heat exchanger 19, the high-pressure receiver 21, the accumulator 27, and the pipes connecting them, all of which are included in the heat source circuit 120a of the outdoor unit 120.

[0122] The amount of non-azeotropic refrigerant mixture pre-filled in the outdoor unit 120 is, for example, two to three times the amount of R32 refrigerant required for the entire refrigerant circuit 110 when R32 refrigerant is filled into the refrigerant circuit 110 in which the liquid refrigerant pipes 5a, 5b, 5c, and 5d and the gas refrigerant pipe 6 are set to the first length.

[0123] In this embodiment, in order to increase the amount of refrigerant that can be pre-filled into the outdoor unit 120, the diameter of the pipes in the outdoor unit 120 is made larger than the diameter of the pipes in the indoor units 30a, 30b, 30c, and 30d.

[0124] In addition, in order to ensure that the amount of refrigerant pre-filled in the outdoor unit 120 is sufficient to meet the amount of refrigerant required for the entire refrigerant circuit 110, the volume ratio of the outdoor heat exchanger 15 to the total volume of the indoor heat exchangers 35a, 35b, 35c, and 35d is set to 3 or more.

[0125] Furthermore, by setting the volume ratio of the high-pressure receiver 21 to the outdoor heat exchanger 15 within the range of 0.04 to 0.6, the amount of refrigerant pre-filled in the outdoor unit 120 can easily satisfy the amount of refrigerant required for the entire refrigerant circuit 110.

[0126] The installation work of the air conditioning apparatus 100 comprises the steps of installing the outdoor unit 120 and the indoor units 30a, 30b, 30c, and 30d at the installation locations, connecting the outdoor unit 120 to the indoor units 30a, 30b, 30c, and 30d via the liquid refrigerant pipes 5a, 5b, 5c, and 5d and the gas refrigerant pipe 6, and sending the refrigerant filled in the outdoor unit 120 to the refrigerant circuit 110.

[0127] In the process of sending the refrigerant filled in the outdoor unit 120 to the refrigerant circuit 110, the liquid-side shut-off valves 25a, 25b, 25c, and 25d and the gas-side shut-off valve 26 are opened, thereby filling the refrigerant circuit 110.

[0128] (4) Features (4-1) In the air conditioning apparatus 100, the outdoor unit 120 and the indoor units 30a, 30b, 30c, and 30d are connected at the installation location via liquid refrigerant pipes 5a, 5b, 5c, and 5d and gas refrigerant pipe 6 to form a refrigerant circuit 110. The refrigerant filled into the refrigerant circuit 110 is a non-azeotropic refrigerant mixture whose temperature glide during evaporation and condensation is 1°C or more. The lengths of the liquid refrigerant pipes 5a, 5b, 5c, and 5d and the gas refrigerant pipe 6 are determined depending on the installation positions of the outdoor unit 120 and the indoor units 30a, 30b, 30c, and 30d. The lengths of the liquid refrigerant pipes 5a, 5b, 5c, and 5d and the gas refrigerant pipe 6 are set in advance to a first length L1 (for example, L1 = 30 m) that makes it unnecessary to additionally fill the refrigerant circuit 110 with refrigerant. The outdoor unit 120 is pre-filled with an amount of refrigerant corresponding to the amount of refrigerant required for the refrigerant circuit 110 when the liquid refrigerant pipes 5a, 5b, 5c, and 5d and the gas refrigerant pipe 6 have the first length L1.

[0129] It is not easy to charge a non-azeotropic refrigerant mixture on-site while maintaining its composition ratio. Therefore, in this air conditioning system 100, the outdoor unit 120 is pre-charged with the refrigerant, eliminating the need for on-site charging, thereby maintaining the composition ratio of the non-azeotropic refrigerant mixture.

[0130] (4-2) In particular, when using R454C, which has a temperature glide of 5° C. or more during evaporation and condensation, it is difficult to maintain the composition ratio when charging the refrigerant on-site. Therefore, in this air conditioning apparatus 100, there is a significant advantage in that the composition ratio of the non-azeotropic refrigerant mixture is maintained by pre-charging the outdoor unit 120 with the refrigerant.

[0131] (4-3) The liquid refrigerant pipes 5a, 5b, 5c, and 5d are preferably 2.5-minute pipes (outer diameter 7.93 mm) or longer. When using a non-azeotropic refrigerant mixture with a large pressure loss, the diameter of the liquid refrigerant pipes 5a, 5b, 5c, and 5d must be increased, which increases the amount of refrigerant to be charged. The greater the amount of refrigerant to be charged, the greater the risk that the refrigerant composition will change during on-site charging. Therefore, in this air conditioning apparatus 100, there is a significant advantage to pre-charging the outdoor unit 120 with the refrigerant, in that the composition ratio of the non-azeotropic refrigerant mixture can be maintained.

[0132] However, if the actual piping lengths of the liquid refrigerant pipes 5a, 5b, 5c, and 5d and the gas refrigerant pipe 6 exceed the first length L1, additional refrigerant charging will be required, further increasing the risk of a change in the refrigerant composition ratio. In order to reduce the risk of a change in the composition ratio in such a situation, 2.5-section pipes are suitable for the liquid refrigerant pipes 5a, 5b, 5c, and 5d from the standpoints of both "suppressing pressure loss" and "suppressing the amount of additional refrigerant charged."

[0133] (4-4) The amount of the non-azeotropic refrigerant mixture pre-filled in the outdoor unit 120 is two to three times the amount of R32 refrigerant that would be required for the entire refrigerant circuit 110 if a single R32 refrigerant were to be filled into the refrigerant circuit 110 in which the liquid refrigerant pipe 5 and the gas refrigerant pipe 6 are set to the first length L1.

[0134] Some non-azeotropic refrigerants require two to three times the amount of R32 refrigerant, which has zero temperature glide, and there is a high risk that the composition ratio of such refrigerants will change when they are filled on-site. Therefore, in this air conditioning system 100, there is a great advantage in that the composition ratio of the non-azeotropic refrigerant is maintained by pre-filling the outdoor unit 120 with the refrigerant.

[0135] (4-5) Since the diameter of the pipes in the outdoor unit 120 is larger than the diameter of the pipes in the indoor units 30a, 30b, 30c, and 30d, the amount of refrigerant that can be pre-filled into the outdoor unit 120 can be increased.

[0136] (4-6) The ratio of the volume of the outdoor heat exchanger 15 to the total volume of the indoor heat exchangers 35a, 35b, 35c, and 35d is equal to or greater than 3. This allows the amount of refrigerant pre-filled in the outdoor unit 120 to satisfy the amount of refrigerant required for the entire refrigerant circuit 110.

[0137] (4-7) The high-pressure receiver 21 is connected between the outdoor heat exchanger 15 and the expansion valve 23. The volume ratio of the high-pressure receiver 21 to the outdoor heat exchanger 15 is within a range of 0.04 to 0.6. The amount of refrigerant that can be pre-charged into the outdoor unit 120 can include an amount of refrigerant equivalent to the internal volume of the high-pressure receiver 21.

[0138] (4-8) The refrigerant circuit 110 is provided with a liquid-gas heat exchanger 19 that exchanges heat between a high-pressure liquid refrigerant and a low-pressure gas refrigerant. The liquid-gas heat exchanger 19 is a double-pipe heat exchanger. The amount of refrigerant that can be pre-filled into the outdoor unit 120 can include an amount of refrigerant equivalent to the internal volume of the liquid-gas heat exchanger 19.

[0139] (5) Other The worker installing the air conditioning device 100 determines whether the lengths of the liquid refrigerant pipes 5a, 5b, 5c, and 5d and the gas refrigerant pipe 6 required for the installation of the air conditioning device 100 are equal to or shorter than the first length L1.

[0140] If the lengths of the liquid refrigerant pipes 5a, 5b, 5c, 5d and the gas refrigerant pipe 6 are less than the first length L1, the amount of refrigerant filled in the outdoor unit 120 is the same as or greater than the required amount of refrigerant, so the additional refrigerant filling step is not necessary. Therefore, the additional refrigerant filling step is not performed, and the outdoor unit 120 and the indoor units 30a, 30b, 30d are connected via the liquid refrigerant pipes 5a, 5b, 5c, 5d and the gas refrigerant pipe 6, and then the installation work is completed.

[0141] In other words, the amount of refrigerant filled in the outdoor unit 120 is equal to or greater than the amount of refrigerant required in the refrigerant circuit 110 when the liquid refrigerant pipes 5a, 5b, 5c, and 5d and the gas refrigerant pipe 6 are equal to or shorter than the first length L1.

[0142] On the other hand, if the lengths of the liquid refrigerant pipes 5a, 5b, 5c, and 5d and the gas refrigerant pipe 6 exceed the first length L1, the refrigerant pre-filled in the outdoor unit 120 is insufficient to meet the required amount of refrigerant, and therefore a step of additionally filling the refrigerant is required.

[0143] Therefore, a refrigerant additional charging step is performed, and an amount of refrigerant corresponding to the lengths of the liquid refrigerant pipes 5a, 5b, 5c, and 5d and the gas refrigerant pipe 6 is additionally charged into the refrigerant circuit 110. The refrigerant is additionally charged, for example, through the service port of the liquid side shut-off valves 25a, 25b, 25c, and 25d or the gas side shut-off valve 26.

[0144] Although the embodiments of the present disclosure have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the present disclosure as defined in the claims.

[0145] DESCRIPTION OF SYMBOLS 1, 100 Air conditioning apparatus 5 Liquid refrigerant piping (piping) 5a, 5b, 5, 5c Liquid refrigerant piping (piping) 6 Gas refrigerant piping (piping) 10, 110 Refrigerant circuit 11 Compressor 15 Outdoor heat exchanger (heat exchanger) 20, 120 Outdoor unit (heat source unit) 20a, 120a Heat source circuit 21 High-pressure receiver 23 Expansion valve (pressure reducer) 24a, 24b, 24c, 24d Second expansion valve (pressure reducer) 25 Liquid side stop valve (first stop valve) 25a, 25b, 25c, 25d Liquid side stop valve (first stop valve) 26 Gas side stop valve (second stop valve) 30 Indoor unit (utilization unit) 30a, 30b, 30c, 30d Indoor unit (utilization unit) L1 First length

[0146] International Publication WO2013 / 111180

Claims

1. A heat source unit (20) configured to form a refrigerant circuit (10) by being connected to a utilization unit (30) via piping (5, 6) at an installation location, wherein the refrigerant filled into the heat source unit is a non-azeotropic refrigerant having a temperature glide of 1°C or more during evaporation and condensation, and the heat source unit is pre-filled with an amount of the refrigerant required for the refrigerant circuit (10) when the length of the piping (5, 6) is a first length (L1) at which additional filling of the refrigerant into the refrigerant circuit (10) is unnecessary.

2. The heat source unit (20) according to claim 1, configured so that the refrigerant circuit (10) is formed by connecting one of the utilization units (30).

3. The heat source unit (20) according to claim 1, wherein the refrigerant circuit (10) is formed by connecting a plurality of the utilization units (30a, 30b, 30c, 30d) in parallel.

4. The heat source unit (20) according to any one of claims 1 to 3, wherein the refrigerant has a temperature glide of 5°C or more during evaporation and condensation.

5. The heat source unit (20) according to any one of claims 1 to 4, configured to be connected to the piping (5) having a length of 2.5 min (outer diameter 7.93 mm) or more through which a liquid refrigerant or a gas-liquid mixed refrigerant flows.

6. The heat source unit (20) according to claim 5, wherein the piping (5) is a 2.5-part pipe (outer diameter 7.93 mm).

7. A heat source unit (20) as described in any one of claims 1 to 6, wherein the amount of the refrigerant pre-filled in the heat source unit (20) is 2 to 3 times the amount of R32 refrigerant required in the entire refrigerant circuit (10) when the refrigerant circuit (10) in which the piping (5, 6) is set to the first length is filled with R32 refrigerant.

8. The heat source unit (20) according to any one of claims 1 to 7, wherein the first length is 30 m.

9. A heat source unit (20) as claimed in any one of claims 1 to 8, comprising: a first shut-off valve (25); a second shut-off valve (26); and a heat source circuit (20a) configured to form part of the refrigerant circuit (10), the heat source circuit (20a) including a compressor (11), a heat exchanger (15), and a pressure reducer (23), the compressor (11), the heat exchanger (15), and the pressure reducer (23) being connected in sequence, and the heat source circuit (20a) further including a high-pressure receiver (21) connected between the heat exchanger (15) and the pressure reducer (23).

10. The heat source unit (20) according to claim 9, wherein the volume ratio of the high-pressure receiver (21) to the heat exchanger (15) is within the range of 0.04 to 0.6.

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